GOLO is based on the concept that getting your insulin under control - rather than simply reducing caloric intake or cutting out entire food groups - is the key to a properly functioning metabolism; once your metabolism is working better, you can lose weight and keep it off more easily, according to the company's website.

There are several hormones that are thought to be involved in appetite, metabolism, and weight management, and GOLO focuses on insulin, which is supposed to regulate your blood sugar. Simply put, when your insulin isn't doing its job of distributing energy to your cells, the sugar stays in your blood and your body stores the extra as fat.

The idea behind GOLO is that it'll get your insulin and blood sugar levels where they belong, thus helping you use energy efficiently. The meal plan itself is mix-and-match, according to Jennifer Brooks, the company's president and co-founder.

A booklet lists permissible foods (all of which are readily available whole foods like meats, vegetables, and fruits) with guidelines for how much you can have at each meal. You then pick one to two servings from each category: proteins, carbs, vegetables, and fats to create your meal; this combo, she says, is designed to keep your blood sugar steady and stave off hunger.

The Golo Diet Cookbook Everyday: 100 Tasty, Healthy, Good Dishes